Stuff

We have three new polls so far today. TNS have put out a new GB poll, which has topline figures of CON 33%(nc), LAB 32%(nc), LDEM 8%(+1), UKIP 16%(-1), GRN 5%(+1) – clearly no significant change since their previous poll (tabs are here).

ComRes have a new poll of the 40 Labour held constituencies in Scotland (that is excluding Falkirk, where Eric Joyce sat out his term as an independent). In 2010 the share of vote in these seats was CON 14%, LAB 51%, SNP 19%, LDEM 14%. The new ComRes poll found support standing at CON 13%(-1), LAB 37%(-14), SNP 43%(+24), LDEM 2%(-12). The seven point SNP lead represents a swing of 19 points from Lab to SNP, the equivalent of a sixteen point SNP lead in a national Scottish poll (tabs are here).

Finally YouGov have a new London poll for the Evening Standard, which has topline figures of CON 34%(+2), LAB 45%(+1), LDEM 8%(+1), UKIP 8%(-2), GRN 4%(-1) – changes are from YouGov’s previous London poll a month ago. The eleven point Labour lead represents a swing of 4.5 points from Con to Lab since the general election, the equivalent of a two point Labour lead in a national GB poll (tabs are here).

How well did Election Forecast, May2015 and Electoral Calculus do in predicting today’s Ashcroft constituency polls?

The short answer is that EF did better than the other two, but that this show some consistent biases that might be worth bearing in mind when using their projections In future.

May2015 only gives the projected winner’s margin over the runner-up and so the only way of assessing the performance of this model is to compare this margin with that shown in the Ashcroft polls, and then I turn see how the discrepancies compare with those shown by EF and EC. In the analyses reported below, I have concentrated on the CVI measure as this is the one that everyone seems to take seriously. (I still think there is a question about whether this will prove to be the best predictor of the actual election results).

For May2015 its margins were on average 6.96% different from Ashcroft’s with some larger and some smaller and particularly big discrepancies in the cases of Camborne and Redruth and Sheffield Hallam. For EC the figure for the mean absolute discrepancy was slightly larger (7.56%), with particular problems arising in the same two constituencies. In contrast with this the EF margins were much closer to Ashcroft’s (mean absolute discrepancy: 3.75%).

As is often the case The Election Forecast projections are more accurate than those of the other two models. It is not at all surprising that it outperforms EC with this batch of seats. Unlike, EC it makes use of Ashcroft constituency polls, and all eight seats were polled last September. I have to admit that I don’t really understand why May2015 performs so badly in these benchmarking tests. Like EF is uses Ashcroft data, but for some reason it doesn’t seem to make good use of this information.

By using the Euclidean Distance metric , it is possible to compare the accuracy with which EF and EC predict the VIs for the five GB-wide parties. In line with the analysis above, the EF projections were closer to the CVI scores (mean Euclidean Distance: 7.28) than were those generated by the EC model (mean Euclidean Distance: 11.53). A score of 7.28 represents a greater level of accuracy than the EF model routinely achieves in previously unpolled constituencies. The reason for this is that the September polling data was incorporated into the database and the model now benefits from the use of that information.

So, as usual we find that Election Forecast is better than its competitors at predicting Ashcroft constituency results. It remains to see whether this will also make it a better predictor of the GE results.

In the past I have looked at systematic biases shown by the different models. In previously unpolled seats, all have shown a bias in favour of Labour. But in the last batch (all revisited by Ashcroft) this pattern was reversed in the case of EF. With the current batch there was a small and non-significant bias in Favour of Labour. I think there is reason to suspect that the model’s biases are different in previously polled seats, and I am reluctant to try to draw any generalizations from the current batch of results.

That said, EF reliably overstated the VIs of both the Greens and Ukip in the current batch. In the case of Ukip all eight projected Ukip VIs were higher than the CVI figures the emerged in today’s polls. This may in part be a quirk of the model’s behaviour in repolled seats, though we have seen reliable Green overestimation in the past (e.g., in the December batch of polls). Another possibility is that support for the smaller parties is being squeezed in these tightly contested marginal seats. Given the distortions introduced by looking at repeatedly polled seats, I don’t think it is safe to conclude that EF more generally overstates Green and Ukip support.

“In his forecast – which will be updated every week until election day – YouGov President Peter Kellner looks at the latest polling data, as well as the state of the campaign and observations from past elections, to share his best guess of what he thinks the result will actually be when all the votes are counted.”

Our Nowcast is based on a sophisticated statistical model that combines the respondents we have in each seat with modelled observations from similar types of people across the country. In maths-speak, it is a hierarchichal Bayesian model using multilevel regression post-stratification, and was originally developed by Professor Andrew Gelman of Columbia University and was extended and applied by YouGov’s Chief Scientist Professor Doug Rivers of Stanford University

Not really. It’s only large in numbers of seats. In terms of VI, Keller’s forecast is just CON on ~37% and LAB on 32 or 33. Which is in MOE of quite a few polls we’re seeing now. It’s not an “enormous amount of change”.

Maybe it is more far-fetched with the Lib Dem prediction of 30 seats, I’m not sure what VI that requires

I am assuming that Kelner is ‘guessing’ that Labour will recover in Scotland that is why the SNP seat count is down but crash and burn in England.

The Labour campaign will have to do something that will simultaneously make them more popular in Scotland but less popular in England. So is Kelner guessing that Labour is going to do something to help their position in Scotland to the detriment of their position in England seems unlikely?

One thing that hasn’t been noted is that if the Ayes had won just a third of 2010 Tory voters over (as opposed to about 2%) then they would have (very narrowly) won. Whether they could have done so, especially while still having such brilliant success winning over SLAB voters, is perhaps doubtful, and depends on the degree to which SLAB voters voted Aye due to promises like “No more Tory governments!” as opposed to non-partisan reasons.

MOE has no relevance in this context. It is the change from actual VI now to actual votes on May 7th that is of interest. Given the snails-pace rates of change over the last months, 37 – 32 or 33 would be large.

So I am riding on a Greyhound Bus through the mountains of British Columbia heading for a appointment with the British Consulate in Vancouver and internet connectivity is intermittent – maybe others have already raised it but there are some interesting factors:

1. UKIP are clearly spoiling Cameron and the Conservatives chances of taking certain seats like North Cornwall, St Ives and Torbay and that hurts their chances of gaining the largest share of seats in the HoC.

2. Given that LD came within 66 votes of taking Camborne and Redruth in 2010 I am surprised that no one has commented on the fact they have lost 65.2% of their support since. How many centre-left LD MPs are there?

3. I still thinking weighting LD above 33% of 2010 by the pollsters is problematic.

4. Are there seats like Camborne and Redruth where Labour could leap over LD and take it from the Conservatives. If Cambridge is atypical, which Con-LD marginals are “low hanging fruit” for Labour – particularly urban ones?

5. I assume that these eight seats are fairly centre right and quite affluent, and therefore it is very interesting to me that even with the “squeeze” Green ends up with an average 6% to Labour’s 9%. One might wonder where the Green vote will end up on May 7th in safe centre left seats, if it can gain this much support in tightly fought centre-right ones.

6. Comments on Redcar assume that the fact that Green are running the president of a national trade union, with 250,000 members, as their candidate, and then the fact that half the local Labour Council members quit the Party, will have not any impact on the Labour vote. I think OLD NAT made the original post about Labour councillors falling out with each other, and that it was a clip from a newspaper. So I wonder if those Councillors will be working for the Labour candidate or the Green candidate? :)

7. When are the next ICM and Opinium polls and I wonder if Ashcroft will re-poll Brighton-Pavillion, Norwich-South and even poll Bristol West?

PS: When I referred to the polling results, as “dogs breakfast” I was not referring to Lord A, but to the results themselves.

Am intrigued how Solihull goes this time. Libs have won on a knife edge twice in what you would think would be Con territory, largely in part due to the local popularity of their candidate. I fancy Cons this time. We shall see.

An interesting addendum to the Cambridge poll which showed the LD’s 9% ahead.

1. Someone in another place explained that the fieldwork was completed during the university holidays. If so, this could artificially boost the LD score as the LDs tuition fees u-turn was a big negative with student voters (of which their are many in the City of Cambridge).

2. In the same “other place” someone pointed out that Lord A asked two separate questions in Cambridge, the second being “who would you vote for if there was a GE tomorrow?”, which showed Lab 5% ahead of the LDs.

In line with what I said last night these are exactly this morning’s EF figures. What this means is that the Newsnight figures are more up to date than those on the website (which were showing different tallies last night.) I suspect they type in the 10.30pm YouGov poll results before they hand the projections to Newsnight.

As it happens, with each of these projections showing I had downloaded a copy of the current VI profiles for all seats. (I was trying to make sure I had up-to-date copies to use for Ashcroft benchmarking.). I was surprised to find that there was not a single change in the database at these two times.

Two possible inferences from this:

(1) That the four seat Lab/Con margin reduction comes entirely from regression switch-off and not from polling changes or

(2) Perhaps the current list-of-seats list is not updated every time the projection is renewed.

For comparison with the Newsnight prediction, here are, very roughly, the equivalent numbers from the bookies:

Con 285
Lab 270
SNP 43
Lib 26
Plaid 2
Ukip 4
Green 1

An interesting bet is for the Tories to win fewer overall votes but more seats, offered at 22/1 by Paddypower. This is in line with the prevailing thinking that the failure to agree a boundary revision with the Lib Dems has left the Tories at a big disadvantage, but I have noticed that several posts have suggested that the way things are going might make this not the case, in which case the odds are obviously attractive.

Mikey
Look at Victoria Street (by Westminster Abbey) and tell me Vince Cable is not going to give up that department plus his ministerial car to hand it over to someone who has not yet even been named? VC will go with his wallet!

Keller’s forecast is just CON on ~37% and LAB on 32 or 33. Which is in MOE of quite a few polls we’re seeing now.

No it isn’t. MoE is attribute of individual polls, not the average. Labour on 33% is MoE. Cons on 37% when their average is 33% and 37% is higher than they’ve had with any pollster for years means there is a massive systemic bias against them. This is possible, but if it’s true it’s not an MoE effect.

Kellner is relying on substantial changes to occur between now and May 7th. If an election held today produced these results it would mean the pollsters- including YouGov!- were way off.

Only in Britain can the capital city show one party (Labour) with an 11 point lead, and yet the leading newspaper in that city (Evening Standard) is a die-hard supporter of the other (Tories). That just shows that the newspapers are not interested in catering to the views of their readers. They’re more interested in spreading the propaganda of their owners.